1. Field of the Invention
The present invention relates to a camera blade driving device that is carried, for example, on a camera and that is capable of blocking part or all of light passing through an exposure aperture, and more particularly to a camera blade driving device that has an electromagnetic actuator including a rotor by which a blade is driven.
2. Description of the Related Art
As an example of a conventional camera blade driving device for use in a camera, there is known a driving device in which an electromagnetic actuator, which is made Up of upper and lower frame members coupled to each other for rotatably supporting a rotor, a magnetizing coil wound onto the upper and lower frame members, a cylindrical yoke attached to the upper frame member, etc., is joined to a base plate having an exposure aperture by means of, for example, a screw and by which a shutter blade is opened and closed or is driven to stop down the aperture (see Japanese Unexamined Patent publication No. 2002-55376).
In this conventional device, the electromagnetic actuator is pre-unitized and is joined to the base plate, which is individually prepared, by means of a screw or the like. Therefore, since an assembly step of preassembling only the electromagnetic actuator and an attachment step of attaching the electromagnetic actuator that has been assembled to the base plate when the device is manufactured are required, the manufacturing procedure becomes complicated, and, since the electromagnetic actuator is pre-unitized, the number of constituent elements rises, and, as a result, the device is increased in cost, is complicated in structure, and is increased in size.
The present invention has been made in consideration of the problems of the conventional device. It is therefore an object of the present invention to provide a camera blade driving device that is simplified in manufacturing processes, is simplified in structure, is reduced in size, and is suitable especially for a small digital camera by reducing the number of constituent elements to the utmost.
A camera blade driving device of the present invention that achieves the aforementioned object has a base plate having an exposure aperture; a blade supported pivotably on a supporting shaft on the base plate and capable of blocking part or all of light passing through the aperture while facing the aperture; and an electromagnetic actuator for driving the blade; the electromagnetic actuator having a frame member joined to the base plate; a rotor one end of which is supported by the frame member and an opposite end of which is supported by the base plate, the rotor having a driving pin by which a driving force is exerted onto the blade and rotating within a predetermined angular range; a magnetizing coil wound onto the frame member and the base plate; and a yoke provided outside the coil substantially coaxially with the rotor.
According to this structure, the rotor is rotatably supported by the frame member and the base plate, and the coil is wound onto the frame member and the base plate. Therefore, the electromagnetic actuator can be simultaneously assembled in a step of attaching various components to the base plate. In other words, unlike the conventional device, the number of necessary frame members is only one, and a fastening component, such as a screw, is not needed since the coil is wound onto the frame member and the base plate while rotatably supporting the rotor. Therefore, the number of components can be lessened, the structure can be simplified, and costs can be reduced. Additionally, the electromagnetic actuator can be simplified in structure and be reduced in height, and, accordingly, the device can be reduced in size and in thickness.
The aforementioned device may be structured such that one of the frame member and the base plate has a fitting convex portion used to connect the two components by fitting, and the other one of the frame member and the base plate has a fitting concave portion to accept the fitting convex portion.
According to this structure, the frame member can be connected to the base plate while being positioned with respect thereto merely by fitting the fitting convex portion into the fitting concave portion, and an attachment process can be easily performed.
The aforementioned device may be structured such that the base plate has a projection that protrudes outward in a radial direction with respect to the aperture, and the frame member is connected to the projection so as to rotatably support the rotor in cooperation with the projection, and the coil is wound onto the projection and the frame member so as to fasten the frame member to the projection.
According to this structure, the coil is wound so as to fasten the frame member to the projection in the state where the frame member is connected to the projection of the base plate, and the rotor is rotatably supported, and therefore the coil can be easily wound, and the frame member can be firmly connected to the base plate without a dedicated screw.
The aforementioned device may be structured such that the rotor is disposed so that a center of an angular range where the rotor rotates is situated substantially on a straight line passing through the center of the aperture and extending in the radial direction, and the coil is wound in a direction substantially perpendicular to the straight line.
According to this structure, the angular range where the rotor can rotate can be greatly set while employing the structure in which the frame member is connected to the base plate, and the coil is wound onto the frame member and the base plate.
The aforementioned device may be structured such that the blade is a single shutter blade or a single diaphragm blade used to open and close the aperture, and the driving pin is connected directly to the single shutter blade or the single diaphragm blade.
According to this structure, the driving pin directly drives the single shutter blade or the single diaphragm blade by rotation of the rotor, and the single shutter blade or the single diaphragm blade opens and closes the aperture or performs stopping-down/nonstopping-down. Therefore, the structure can be simplified, and it is possible to obtain a small-sized camera shutter device or a small-sized camera diaphragm device having a small height (a small thickness), which is suitable for, e.g., a digital camera.
The aforementioned device may be structured such that the blade is a pair of shutter blades or a pair of diaphragm blades used to open and close the aperture, and the driving pin is connected to the pair of shutter blades or the pair of diaphragm blades through a connecting arm swingably supported by the base plate.
According to this structure, the driving pin drives the pair of shutter blades or the pair of diaphragm blades by rotation of the rotor through the connecting arm. Therefore, the structure can be simplified, and it is possible to obtain a small-sized camera shutter device or a small-sized camera diaphragm device having a small height (a small thickness), which is suitable for, e.g., a digital camera.
Also, a camera blade driving device of the present invention that achieves the aforementioned object has a base plate having an exposure aperture; a blade supported pivotably on a supporting shaft on the base plate and capable of blocking part or all of light passing through the aperture while facing the aperture; and an electromagnetic actuator for driving the blade; the electromagnetic actuator having a frame member joined to the base plate; a rotor one end of which is supported by the frame member and an opposite end of which is supported by the base plate, the rotor having a driving pin by which a driving force is exerted onto the blade and rotating within a predetermined angular range; and a magnetizing coil wound onto the frame member and the base plate.
According to this structure, the rotor is rotatably supported by the frame member and the base plate, and the coil is wound onto the frame member and the base plate. Therefore, the electromagnetic actuator can be simultaneously assembled in a step of attaching various components to the base plate. In other words, unlike the conventional device, the number of necessary frame members is only one, and a fastening component, such as a screw, is not needed since the coil is wound onto the frame member and the base plate while rotatably supporting the rotor. Therefore, the number of components can be lessened, the structure can be simplified, and costs can be reduced. Additionally, the electromagnetic actuator can be simplified in structure and be reduced in height, and, accordingly, the device can be reduced in size and in thickness.